Recently techniques have become available for the noninvasive stimulation of the human cortex and deep proximal peripheral nerves. Stimulation can be with a high-voltage, extremely brief electrical pulse or with magnetic stimulation. One purpose is to use these methods for noninvasive localization of different parts of the human cortex including motor cortex, sensory cortex and language cortex. Another purpose is to study cortical physiology in different disease states. We have continued to make advances in understanding the technical aspects of magnetic stimulation, defining the optimal method to map different body part representations in motor cortex. Extensive effort has been devoted to the study of the inhibitory effects of brain stimulation. We have shown that at least in the late part of the silent period after an evoked response, a reduction in the excitability of the spinal motor neuron pool does not play a major role in determining the phenomenon, but that it is probably caused by lack of central drive. We have also identified inhibitory effects without a preceding excitation in both contralateral and ipsilateral limbs, mapped the topography of these effects, and studied the physiology. We have studied reaction time to brain stimulation and found that when appropriate stimuli are delivered to the motor cortex that people can respond faster than to any other known stimulus. Additionally, we have found that magnetic stimulation can speed the response to any other stimulus. Following up our previous studies that showed reorganization of motor cortex pathways following amputation of a limb, we studied plastic reorganization of motor pathways in normal volunteers by recording motor evoked potentials in arm muscles before, during, and after anesthetic block of the forearm and hand. Minutes after anesthesia initiation, the potential amplitudes increased in muscles immediately proximal to the anesthetic block, returning to pre-anesthesia levels minutes after anesthesia discontinuation. We have also studied the visual cortex and demonstrated that it was possible in three of six patients to produce brief visual images in blind patients. This technique may identify patients suitable for a visual prosthesis that uses direct brain stimulation.